A method for arranging sensors for monitoring the stress state of a jacket

Abstract

The present invention discloses a method for arranging sensors for monitoring the stress state of a jacket, belonging to the technical fields of structural health monitoring and ocean engineering. By means of the acceleration of wave particles and water flow at the main legs of the jacket, the horizontal resultant force of the waves on the main legs of the jacket is obtained; and in combination with wind pressure, a deep convolutional neural network model is used to determine the UC value of the hot spot area of the member, and then the monitoring points on the jacket are determined for the installation and arrangement of sensors. The present invention can greatly improve the accuracy of monitoring and avoid data fluctuations caused by processing reasons. At the same time, the present invention selects the monitoring points in one main leg direction, and the selected measuring points can be conveniently installed on site; the determined positions of the sensor arrangement are all on the windward and wave side, ensuring monitoring at relatively dangerous positions, improving the reliability of monitoring, and making the monitoring results more guiding.

Description

Technical Field

[0001] The present invention relates to the technical fields of structural health monitoring and offshore engineering, and particularly relates to a method for arranging sensors for monitoring the stress state of a jacket platform. Background Art

[0002] As an important infrastructure in the fields of offshore oil and gas development, etc., the jacket platform of an offshore platform is under the long-term complex marine environmental loads, such as wind, wave, current, sea ice, etc., and it is impossible to observe in real time. Moreover, the jacket structure is huge and there are numerous members. Therefore, it is impossible to install sensors on each member for monitoring. Considering the cost and effect, it is necessary to monitor the key points of the jacket platform. Therefore, through the monitoring of the key points, the stress state of the entire jacket platform can be deduced, providing a scientific basis for later maintenance. In traditional methods, during the selection of key points for arranging sensors, less consideration is given to the influence brought by the actual environmental conditions where the offshore platform is located. Therefore, the monitored data cannot well reflect the true stress conditions of the members. From the perspective of reliability, the guiding significance of the monitoring results is not strong. Summary of the Invention

[0003] The present invention discloses a method for arranging sensors for monitoring the stress state of a jacket platform to overcome the above technical problems.

[0004] To achieve the above object, the technical solution of the present invention is as follows:

[0005] A method for arranging sensors for monitoring the stress state of a jacket platform includes the following steps:

[0006] S1: Establish a finite element model of the jacket platform and obtain the hot spot areas of the members in the jacket platform;

[0007] S2: Obtain the sea current wave particle acceleration and water flow acceleration at the main legs of the jacket platform to obtain the horizontal resultant force of the waves on the main legs of the jacket platform;

[0008] S3: According to the meteorological data of the sea area where the jacket platform is in service, determine the windward side of the finite element model of the jacket platform and determine the wind pressure applied to the jacket platform;

[0009] S4: Based on the finite element model of the jacket platform, the horizontal resultant force of the waves on the main legs of the jacket platform, the windward side of the finite element model of the jacket platform, and the wind pressure, determine the UC value of the hot spot area of the member based on a deep convolutional neural network model; to determine the members of the jacket platform that need to be monitored, and then determine multiple monitoring points on the jacket platform, that is, the sensor arrangement positions;

[0010] S5: Install sensors at the monitoring points of the members on the jacket platform to complete the arrangement of the sensors.

[0011] Further, the method for obtaining the hot spot areas of the members in the jacket is as follows:

[0012] Based on the finite element model of the jacket and the fatigue life assessment method, determine the stress concentration factor of the points on the members.

[0013] When the stress concentration factor of the points on the members is greater than the set threshold value, the points on the members belong to the hot spot areas.

[0014] Further, in S2, the hydrodynamic wave particle acceleration and the water flow acceleration at the main legs of the jacket are obtained as follows:

[0015] ,

[0016] In the formula: represents the hydrodynamic wave particle acceleration and the water flow acceleration at the main legs of the jacket; is the wave height; is the wave period; is the water depth; is the wave number; is the vertical coordinate in the direction from the sea surface to the seabed; is the wave circular frequency; is the time; is the horizontal coordinate at the main legs of the jacket;

[0017] The horizontal resultant force of the waves on each main leg of the jacket is obtained as follows:

[0018] ,

[0019] In the formula: represents the horizontal resultant force per unit length of the waves on the main legs of the jacket; is the seawater density; is the inertia force coefficient; is the radius of the main legs of the jacket; is the correction coefficient; is the velocity of the seawater relative to the main legs; is the correction coefficient of the jacket weight.

[0020] Further, in S4, the multiple monitoring points on the jacket are in the same main leg direction of the jacket.

[0021] Further, in S4, the method for determining the monitoring points of the members on the jacket is as follows:

[0022] Determine the hot spot areas of the members with the UC value greater than the set UC value threshold as the monitoring points of the members on the jacket.

[0023] Further, in step S5, the method for arranging sensors at the monitoring points of the members on the jacket is as follows:

[0024] S51: At the positions of the monitoring points of the members on the jacket, draw a number of positioning lines parallel to the axis of the member evenly in the circumferential direction of the member;

[0025] S52: After the projection of the center line of the first pipe connection of the welded sealing chamber on the member coincides with the positioning line, weld the welded sealing chamber;

[0026] S53: Weld one end of the first cable protection pipe to the first pipe connection, and make the projection of the center line of the first cable protection pipe on the member coincide with the positioning line;

[0027] S54: Make the center line of the first cable protection pipe coincide with the axis of the designed position of the arc-shaped plate plug hole corresponding to the first sensor by means of fire-taking adjustment;

[0028] S55: Weld one end of the second cable protection pipe to the second pipe connection of the welded sealing chamber, and make the center line of the second pipe connection coincide with the axis of the designed position of the arc-shaped plate plug hole corresponding to the second sensor at the other end by means of fire-taking adjustment; and conduct a pressure test;

[0029] S56: After the pressure test is completed, weld and fix the arc-shaped plate, and weld the clamping bases of the first sensor / second sensor;

[0030] S57: After the welding work of the clamping bases is completed, install the first sensor and multiple second sensors simultaneously, and conduct tests;

[0031] S58: After the test is completed, weld the watertight outer shell to complete the installation of the sensors at the monitoring points.

[0032] Further, after step S5, it also includes:

[0033] S6: After the jacket is installed in the service sea area of the jacket, obtain the measured axial force and bending moment of the monitoring points of the member through the monitoring data of the sensor, so as to obtain the deviation between the theoretical axial force and bending moment and the measured axial force and bending moment according to the theoretical axial force and bending moment of the monitoring points of the member, so as to guide the staff at the construction site of the relevant project for the layout of the jacket to correct the layout of the sensor.

[0034] Beneficial effects: A method for arranging sensors for monitoring the stress state of a jacket platform obtains the horizontal resultant force of waves on the main legs of the jacket platform through the acceleration of sea current wave particles and the water flow acceleration at the main legs of the jacket platform; and based on the finite element model of the jacket platform, the horizontal resultant force of waves on the main legs of the jacket platform, and the wind pressure against the wind obtained from the meteorological data of the sea area where the jacket platform is in service, determines the UC value of the hot spot area of the member based on a deep convolutional neural network model; to determine the jacket platform members that need to be monitored, and then determine multiple monitoring points on the jacket platform, and install and arrange sensors at the monitoring points. Through finite element analysis and calculation, the present invention monitors key weak parts, which can reduce the on-site construction workload and focus on monitoring relatively dangerous points. By monitoring key members according to the preliminary results of finite element calculation, the accuracy of monitoring can be greatly improved, and data fluctuations caused by processing reasons can be avoided. At the same time, the present invention selects monitoring points in one main leg direction, and the selected measuring points can be conveniently installed on site under the condition of meeting the UC value selection; the determined positions of sensor arrangement are all on the windward and wave side, ensuring monitoring at relatively dangerous positions, improving the reliability of monitoring, and making the monitoring results more guiding. Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 It is a flowchart of the method for arranging sensors for monitoring the stress state of the jacket platform of the present invention;

[0037] Figure 2 It is a schematic diagram of the UC value of the jacket platform members in the embodiment of the present invention;

[0038] Figure 3 It is a schematic diagram of the measuring point arrangement of the jacket platform in the embodiment of the present invention;

[0039] Figure 4 It is a schematic diagram of arranging 4 sensors circumferentially at the measuring point in the embodiment of the present invention;

[0040] Figure 5 It is a schematic diagram of the protective structure of the measuring point sensor in the embodiment of the present invention;

[0041] Figure 6 It is a schematic diagram of the welding sequence of the sensor clamping base in the embodiment of the present invention;

[0042] Figure 7The layout and calculation block diagram of the measurement points of the jacket in the embodiments of the present invention;

[0043] Figure 8 The schematic diagram of the installation positions of the sensors of the upper module in the embodiments of the present invention.

[0044] Wherein, 1, the first protective pipe connection; 2, the second protective pipe connection; 3, the first wire protection pipe; 5, the second wire protection pipe; 9, the fusion sealing chamber. Specific embodiments

[0045] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0046] This embodiment introduces a method for arranging sensors for monitoring the stress state of a jacket, as shown in Figure 1 and Figure 7 and includes the following steps:

[0047] S1: Establish a finite element model of the jacket and obtain the hot spot areas of the members in the jacket;

[0048] Preferably, the method for obtaining the hot spot areas of the members in the jacket is as follows:

[0049] Based on the finite element model of the jacket, determine the stress concentration factor of the points on the members according to the fatigue life assessment method;

[0050] When the stress concentration factor of the points on the members is greater than the set threshold, the points on the members belong to the hot spot areas;

[0051] Specifically, the establishment of the finite element model of the jacket in this embodiment is a conventional technology in the field. For example, after the finite element model is established, the fatigue life assessment method is used to determine the fatigue damage accumulation rate of the members, such as the S-N curve method (stress-life curve method): according to the S-N curve of the jacket material and the stress history obtained from the finite element analysis, calculate the fatigue damage accumulation of each member under different load conditions. Among them, the S-N curve of the jacket material is obtained through conventional material tests and reflects the fatigue life of the material under different stress amplitudes; the stress history is the process of the stress of a certain point or area in the model changing with time, load change or other parameter changes during the finite element analysis process. Based on this changing process, the fatigue damage accumulation rate, that is, the stress concentration factor, can be obtained;

[0052] In this embodiment, when the stress concentration factor is greater than 3, it is determined that a certain point on the member belongs to the hot spot area. Specifically, through fatigue damage accumulation calculation, the finite element model identifies the points on the member where the fatigue damage accumulates relatively fast, that is, the stress concentration factor is greater than 3, and finally determines the hot spot area on the member. These hot spot areas are the places where fatigue damage is most likely to occur and develop under long-term environmental loads and working loads. For example, at certain positions of the underwater components that are frequently impacted by waves, fatigue damage may accumulate rapidly due to repeated stress cycles.

[0053] S2: Obtain the seabed current wave particle acceleration and water flow acceleration at the main legs of the jacket to obtain the horizontal resultant force of the waves on each main leg of the jacket.

[0054] Preferably, in the said S2, the seabed current wave particle acceleration and water flow acceleration at the main legs of the jacket are obtained as follows:

[0055] ,

[0056] In the formula: represents the seabed current wave particle acceleration and water flow acceleration at the main legs of the jacket; is the wave height; is the wave period; is the water depth; is the wave number; is the vertical coordinate in the direction from the sea surface to the seabed; is the wave circular frequency; is the time; is the horizontal coordinate at the main legs of the jacket;

[0057] The horizontal resultant force of the waves on each main leg of the jacket is obtained as follows:

[0058] ,

[0059] In the formula: represents the horizontal resultant force per unit length of the waves on the main leg of the jacket; is the seawater density; is the inertia force coefficient; is the radius of the main leg of the jacket; is the correction coefficient; is the velocity of the seawater relative to the main leg; is the correction coefficient of the jacket weight.

[0060] S3: According to the meteorological data of the sea area where the jacket is in service, determine the windward side of the finite element model of the jacket and determine the wind pressure applied to the jacket.

[0061] Specifically, obtain the meteorological data of the service sea area of the jacket, and determine the main wind direction in this sea area. Establish a spatial rectangular coordinate system to determine the orientation of each surface, and identify the windward surface of the finite element model of the jacket under the action of this wind direction in the SACS software. Furthermore, combine the sea current wave particle acceleration and water flow acceleration at the main legs of the jacket to obtain the horizontal resultant force of the waves on each main leg of the jacket, and apply it to the finite element model of the jacket to establish a fluid-structure interaction model analysis model, and simulate the stress condition of the jacket under the combined action of complex ocean currents and winds, so as to further determine the windward surface and its wind pressure distribution. Furthermore, it can be ensured that the finally determined monitoring points are located on the side of the main leg with relatively large force;

[0062] S4: Based on the finite element model of the jacket, the horizontal resultant force of the waves on the main legs of the jacket, the windward surface of the finite element model of the jacket, and the wind pressure, determine the UC value of the hot spot area of the member based on the deep convolutional neural network model; to determine the jacket members that need to be monitored, and then determine multiple monitoring points on the jacket, that is, the sensor layout positions;

[0063] Preferably, the multiple monitoring points on the jacket are in the same main leg direction of the jacket;

[0064] Specifically, in this embodiment, apply the horizontal resultant force of the waves on each main leg of the jacket and the wind pressure to the finite element model of the jacket, and determine the UC value of the hot spot area of the member based on the deep convolutional neural network model; to determine the monitoring points of the members on the jacket, and then determine the sensor layout positions on the main legs of the jacket;

[0065] Specifically, take the hot spot area on the member as the key calculation area of the UC value. Within the hot spot area on the member, further determine the specific detailed structure UC value in combination with factors such as the specific geometric shape parameters and stress state of the member, as shown in Figure 2 shown. In this embodiment, a UC value prediction algorithm based on deep learning is adopted. Among them, the deep convolutional neural network model adopted inputs the member structure data through the input layer, including geometric shape parameters, material properties, load conditions, etc., and the output layer outputs the UC value of the member. By training the deep convolutional neural network model, learn the mapping relationship between the member structure data and the UC value:

[0066] Specifically, a large amount of jacket structure data and corresponding UC values are collected, including data such as structural stress, strain, and fatigue damage under different working conditions. These data are used to train a deep convolutional neural network model, adjust the parameters and weights of the model, so that the model can accurately predict the UC value. During the training process, methods such as cross-validation are adopted to improve the generalization ability of the model. By continuously optimizing the neural network model, the prediction accuracy and reliability of the model are improved. For example, adjust the structure, parameters, training methods, etc. of the model to make the model better adapt to complex structural and load conditions. At the same time, combined with actual engineering applications, the model is verified and improved to ensure the practicality and effectiveness of the model;

[0067] Specifically, after the deep convolutional neural network model is trained, the new jacket structure parameters are input into the trained neural network model to predict the UC values of the new jacket members. The deep convolutional neural network model can automatically calculate the UC value of the member according to the input member structure data, that is, the UC value of the hot spot area of the member can be obtained. By analyzing and evaluating the prediction results, the location and quantity of the UC value monitoring points are determined;

[0068] Preferably, the method for determining the monitoring points of the members on the jacket is as follows:

[0069] Determine the hot spot area of the member whose UC value is greater than the set UC value threshold as the monitoring point of the member on the jacket;

[0070] Specifically, the UC value of the member represents the ratio of its bearing capacity to the usage requirements, that is, the ratio of the ultimate bearing capacity of the member to the actual usage bearing capacity. The smaller the UC value, the higher the safety factor of the member and the greater the bearing capacity. On the contrary, it means that the safety factor is lower and the bearing capacity is smaller. The UC value is one of the important indicators for member design and selection. Generally, it is required that the UC value shall not be greater than 1.0 to ensure the safety and reliability of the member during use;

[0071] Specifically, according to the calculation results of the UC values of the hot spot areas of the members, select the members with larger UC values in the hot spot areas as the jacket members that need to be key monitored. Then, select the specific monitoring points (horizontal braces, diagonal braces, and main legs) according to the structural characteristics of the jacket, that is, select the positions that are easy to install and have no interference as the measuring points; In this embodiment, the monitoring points of the jacket members that need to be key monitored are selected in the direction of one main leg, as Figure 3 shown. Specifically, for the horizontally installed jacket, the main leg where the sensor is arranged should be located on the side of the launching slipway to ensure that high-altitude operations are reduced during installation, which is beneficial to inverse calculation and layout installation; Among them, the equipment, horizontal braces, diagonal braces, etc. adjacent to a certain main leg are all in the direction of that main leg;

[0072] Specifically, in this embodiment, when determining the positions of the monitoring points on the members with relatively large UC values, ensure that the distances between the monitoring points of the cross braces and the main legs from the position of the K point of the main leg are greater than 1 meter; symmetrically arrange monitoring points at the cross points of the diagonal braces, and the distances between the monitoring points and the cross points are greater than 1 meter;

[0073] Install sensors at the selected monitoring points. The sensors are symmetrically arranged along the circumferential direction of the member. The number of sensors arranged can be 2, 4, 6, 8... etc. The installation positions of the sensors are not less than 200 mm away from the circumferential and longitudinal welds. As Figure 4 shows a schematic diagram of symmetrically arranging 4 sensors along the circumferential direction of the member;

[0074] S5: Install sensors at the monitoring points on the members of the jacket to complete the arrangement of the sensors;

[0075] Preferably, the method for arranging sensors at the monitoring points on the members of the jacket is as follows:

[0076] S51: At the position of the monitoring point on the member of the jacket, evenly draw a number of positioning lines parallel to the axis of the member in the circumferential direction of the member;

[0077] S52: After the projection of the center line of the first pipe connection 1 at the protruding position at the front end of the welded and sealed cabin 9 on the member coincides with the positioning line, determine the position of the center line of the welded and sealed cabin 9 and weld the welded and sealed cabin 9;

[0078] S53: Weld one end of the first cable protection pipe 3 to the first pipe connection 1 and make the projection of the center line of the first cable protection pipe 3 on the member coincide with the positioning line;

[0079] S54: Make the center line of the first cable protection pipe 3 coincide with the axis of the designed position of the arc-shaped plate plug hole corresponding to the first sensor by means of thermal adjustment;

[0080] Specifically, there are a welded and sealed cabin 9 and multiple sensors at the position of the monitoring point. Among them, there is a pipe connection on the side wall of the welded and sealed cabin 9 for connecting the protection pipe of the sensor connection line; among them, the pipe connection whose projection of the axis on the member coincides with the positioning line is used as the first pipe connection, the sensor corresponding to the first pipe connection is the first sensor, and the other multiple sensors set at the monitoring point are the second sensors, and the other pipe connections on the welded and sealed cabin 9 are the second pipe connections; among them, there are 4 sensors set at the monitoring point of this embodiment, including 1 first sensor and 3 second sensors. Correspondingly, 1 first pipe connection 1 and 3 second pipe connections 2 are set on the welded and sealed cabin, as Figure 5 shown, among them, the projection of the center line of the first pipe connection 1 on the member coincides with the positioning line;

[0081] Among them, when positioning the welding sealed cabin 9, the center line of the first wire routing pipe 3 of the welding sealed cabin 9 must coincide with the projection of the pipe center line on the rod, that is, coincide with the positioning straight line. At the same time, the projections of the corresponding sensor, the center line of the clamping base, and the center line of the metal shell of the sensor on the rod must all coincide with the positioning straight line, and be on the same straight line as the projection of the center line of the first pipe connection 1 of the welding sealed cabin 9;

[0082] Specifically, when positioning and welding the first wire routing pipe 3, one end of the first wire routing pipe 3 is butted with the first pipe connection 1 extending from the welding sealed cabin 9, so that the projection of the center line of the first wire routing pipe 3 on the rod coincides with the positioning straight line, and the axis of the wire routing pipe coincides with the axis of the designed position of the arc plate plug hole (assisted by the arc plate for positioning); with the assistance of the arc plate for positioning, determine the distance between the center of the pipe and the jacket (optionally 69mm ± 5mm). If the distance between the center of the pipe and the jacket is not within the required range, fire adjustment is required. Specifically, when the pipe is installed on site, the prefabricated shape may deviate from the actual situation on site. At this time, the angle of the pipe needs to be finely adjusted on site by heating the pipe with a flame, which is called fire adjustment in the shipbuilding industry and is a conventional technology in this field;

[0083] S55: Weld and fix one end of the second wire routing pipe 5 to the second pipe connection 2 of the welding sealed cabin 9, and make the center line of the second pipe connection 2 coincide with the axis of the designed position of the arc plate plug hole corresponding to the second sensor at the other end by the method of fire adjustment; and conduct a pressure test to determine that the welded welding sealed cabin 9 meets the usage requirements. Among them, the second wire routing pipe is a bent pipe;

[0084] Specifically, since both the welding sealed cabin 9 and the bent pipe work at a water depth of 200 meters underwater, pressure testing must be carried out after welding and installation to confirm that there is no problem with the welding and ensure the overall sealing performance; the method for overall pressure testing of the sealed welding cabin and the bent pipe in this embodiment is as follows: the minimum test pressure is not less than 1.2 times the hydrostatic pressure corresponding to the water depth, the test pressure is 2.6MPa, and the pressure holding time is not less than 2 hours;

[0085] S56: After the pressure test is completed, weld and fix the arc plate, and weld the two clamping bases of each sensor of the first sensor / second sensor;

[0086] Specifically, weld the arc plate to the jacket. The arc plate is vertically positioned and welded on the rod structure, and the arc plate welding requires double-sided welding;

[0087] S57: After the welding work of the clamping base is completed, install the first sensor and the second sensor simultaneously according to the welded clamping base, and conduct tests. Specifically, four sensors at the same measuring point are installed synchronously;

[0088] S58: After the test is completed, weld the watertight housing according to the sensors that have been tested normally to complete the installation of the sensors at the monitoring points.

[0089] Specifically, on one side of the watertight housing of this embodiment connected to the wire routing protection pipe, there is an arc-shaped plate provided with an arc-shaped plate plug hole, and the wire routing protection pipe passes through the arc-shaped plate plug hole and enters the interior of the watertight housing. Among them, use the argon arc welding technology to perform full welding on the watertight housing, and control the ratio of the temperature rise of the sensor in °C to the welding speed in cm / min not to be greater than 7.5.

[0090] Specifically, the sensors of this embodiment are fixed by two clamping bases, and each clamping base fixes one side of the sensor. The clamping base is an existing technology in the field and will not be described in detail here.

[0091] Specifically, when welding the clamping base of this embodiment, it is necessary to meet the diagonal welding process and weld in the order of 1234, as Figure 6 shown. During the welding process, pay attention to ensuring that the same clamping base is completely cooled before welding at the next corresponding serial number position.

[0092] Preferably, after S5, it further includes:

[0093] S6: After the jacket is installed in the jacket service sea area, through the monitoring data of the sensors, obtain the measured axial force and bending moment of the monitoring points of the members, so as to obtain the deviation between the theoretical axial force and bending moment and the measured axial force and bending moment according to the theoretical axial force and bending moment of the monitoring points of the members, in order to guide the staff at the construction site of the relevant projects for the subsequent layout of the jacket to correct the layout of the sensors.

[0094] Specifically, calculate the measured axial force and bending moment of each point according to the layout of the sensors at each monitoring point. The calculation process is as follows:

[0095] Based on the monitoring information of the sensors, establish the calculation formulas for the axial force and bending moment of the cross-section where the monitoring position is located.

[0096] Axial force calculation formula:

[0097] , unit ,

[0098] Bending moment calculation formula:

[0099] , unit ,

[0100] , unit ,

[0101] Wherein: represents the Young's modulus, , with the unit ; represents the cross-sectional area of the pipe, , with the unit ; represents the moment of inertia of the pipe cross-section, , with the unit ; The monitored strain at each measurement point, in clockwise order, is , with the unit ; represents the pipe diameter, represents the wall thickness, represents the influence coefficient of the sensor shield.

[0102] A specific embodiment of the present invention is as follows:

[0103] In this embodiment, the axial force of the jacket of an offshore oil platform project in the South China Sea is verified by an example. The process is as follows:

[0104] 1) Obtain the weighing weight and the center of gravity of the upper module of the offshore oil platform provided by the construction unit;

[0105] 2) According to the drawings of the offshore oil platform, analyze and calculate through finite element software to determine the monitoring points and install sensors, Figure 8 shows a schematic diagram of the installation position of the sensors on the upper module of the jacket;

[0106] 3) According to the input data such as the weight and the center of gravity position of each part, conduct theoretical calculations of the axial force analysis of each leg in the finite element software. The calculation results are shown in Table 1:

[0107] Table 1 Theoretical calculation results of the axial force analysis of the jacket legs

[0108] ;

[0109] 4) A large amount of raw data is obtained through sensor monitoring of the offshore oil platform. The screening and processing of the raw data are mainly carried out through the following method steps:

[0110] a. Preprocess the data sequence X to be analyzed. If the sample mean is not zero, subtract the sample mean from each data point to ensure that the data sequence X is a zero-mean data vector;

[0111] b. Use the Fourier transform to calculate the amplitude spectrum A(f) and the phase spectrum φ(f) of the sequence X, where f is the frequency with the unit of Hz. The amplitude spectrum shows the intensity of different frequency components in the data, while the phase spectrum provides the phase information of these frequency components relative to the starting point of the time series;

[0112] c. Determine the frequency range [fl, fu] to be filtered out (where fl and fu are the lower and upper bounds of the selected frequency range respectively), and set the amplitude A(fi) corresponding to each frequency value fi within this frequency range to zero. By cutting off the unwanted frequency components in the amplitude spectrum, the purpose of data filtering is achieved;

[0113] d. Based on the new amplitude spectrum and the original phase spectrum after being processed by the above steps, perform inverse Fourier transform, and take the real part of the transformation result as the new data sequence X'. After being processed by the above steps, the unwanted frequency components have been removed from the new amplitude spectrum, so the sequence X' is the data sequence after filtering;

[0114] e. Calculate the axial force according to the selected measured data according to the aforementioned axial force calculation formula to obtain the true axial force under the actual condition;

[0115] 5) Compare the theoretical calculation with the actual monitoring,

[0116] As shown in Table 2:

[0117] Table 2 Comparison Table of Theoretical Calculation and Actual Monitoring Data

[0118] ;

[0119] By comparing the theoretical values and the measured values in Table 2, the deviation is less than 5%, verifying the accuracy of the algorithm in this embodiment.

[0120] This embodiment is applied to the jacket structure health monitoring system in ocean engineering to monitor the stress and strain conditions of the jacket part, and has the following beneficial effects:

[0121] 1) Since the jacket is a very large and complex rod structure, it is impossible to install sensors on each rod for monitoring. However, in this embodiment, through finite element analysis and calculation, key weak parts are monitored, which can reduce the on-site construction workload and focus on monitoring relatively dangerous points. By monitoring key rods according to the preliminary results of finite element calculation, the monitoring accuracy can be greatly improved, and data fluctuations caused by processing reasons can be avoided;

[0122] 2) Since the number of sensors installed at each measuring point in this embodiment is an even number, they can be mutually calibrated. The sensor layout adopts circumferential symmetric arrangement. The more points are arranged, the more accurate the measured data is, and the axial force and bending moment of the rod can be accurately calculated, improving the measurement accuracy;

[0123] 3) Because the jacket structure is basically a symmetric structure, in this embodiment, the monitoring points are selected in one main leg direction, and the selected measuring points can be conveniently installed on site under the condition of meeting the UC value selection;

[0124] 4) The positions of the sensor arrangements in this embodiment are all on the "windward and wave" side, ensuring monitoring at the relatively most dangerous positions, improving the monitoring reliability, and making the monitoring results more instructive.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for arranging sensors for monitoring the stress state of a jacket, characterized in that, Including the following steps: S1: Establish a finite element model of the jacket and obtain the hot spot areas of the members in the jacket; S2: Obtain the seastream wave particle acceleration and water flow acceleration at the main legs of the jacket to obtain the horizontal resultant force of the waves on the main legs of the jacket; In S2, the seastream wave particle acceleration and water flow acceleration at the main legs of the jacket are obtained as follows: In the formula: a represents the seastream wave particle acceleration and water flow acceleration at the main legs of the jacket; H is the wave height; T is the wave period; h is the water depth; k is the wave number; z is the vertical coordinate in the direction from the sea level to the seabed; ω is the wave circular frequency; t is the time; x is the horizontal coordinate at the main legs of the jacket; The horizontal resultant force of the waves on each main leg of the jacket is obtained as follows: f = ρC m πR 2 a + λρRv 2 + c In the formula: f represents the horizontal resultant force per unit length of the wave acting on the main leg of the jacket; ρ is the density of seawater; C m is the inertia force coefficient; R is the radius of the main leg of the jacket; λ is the correction coefficient; v is the velocity of seawater relative to the main leg; c is the correction coefficient of the jacket weight; S3: According to the meteorological data of the sea area where the jacket is in service, determine the windward side of the finite element model of the jacket and determine the wind pressure applied to the jacket; S4: Based on the finite element model of the jacket, the horizontal resultant force of the waves on the main legs of the jacket, the windward side of the finite element model of the jacket, and the wind pressure, determine the UC value of the hot spot area of the member based on the deep convolutional neural network model; To determine the jacket members that need to be monitored, and further determine multiple monitoring points on the jacket, that is, the sensor layout positions; S5: Install sensors at the monitoring points of the members on the jacket to complete the layout of the sensors.

2. The method for arranging sensors for monitoring the force state of a jacket according to claim 1, characterized in that, The method for obtaining the hot spot areas of the members in the jacket is as follows: According to the finite element model of the jacket, based on the fatigue life assessment method, determine the stress concentration factor of the points on the member; When the stress concentration factor of the points on the member is greater than the set threshold, the points on the member belong to the hot spot area.

3. A method for arranging sensors for monitoring the stress state of a jacket, according to claim 1, characterized in that In S4, the multiple monitoring points on the jacket are in the same main leg direction of the jacket.

4. A method for arranging sensors for monitoring the stress state of a jacket, as claimed in claim 1, wherein In S4, the method for determining the monitoring points of the members on the jacket is as follows: Determine the hot spot areas of the members with the UC value greater than the set UC value threshold as the monitoring points of the members on the jacket.

5. A method for arranging sensors for monitoring the stress state of a jacket, according to claim 1, characterized in that, In S5, the method for laying out sensors at the monitoring points of the members on the jacket is as follows: S51: At the position of the monitoring point of the member on the jacket, evenly draw a number of positioning lines parallel to the axis of the member in the circumferential direction of the member; S52: After the projection of the center line of the first pipe connection of the welded sealing chamber (9) on the member coincides with the positioning line, weld the welded sealing chamber (9); S53: Weld one end of the first wire protection pipe (3) to the first pipe connection (1) and make the projection of the center line of the first wire protection pipe (3) on the member coincide with the positioning line; S54: Make the center line of the first wire protection pipe (3) coincide with the axis of the designed position of the arc-shaped plate plug hole corresponding to the first sensor by means of thermal adjustment; S55: Weld one end of the second wire protection pipe (5) to the second pipe connection (2) of the welded sealing chamber (9), and make the center line of the second pipe connection (2) coincide with the axis of the designed position of the arc-shaped plate plug hole corresponding to the second sensor at the other end by means of thermal adjustment; and conduct a pressure test; S56: After the pressure test is completed, weld and fix the arc-shaped plate, and weld the clamping bases of the first sensor / second sensor; S57: After the welding work of the clamping bases is completed, install the first sensor and the second sensor simultaneously and conduct tests; S58: After the test is completed, weld the watertight housing to complete the installation of the sensors at the monitoring points.

6. A method for arranging sensors for monitoring the stress state of a jacket, according to claim 1, characterized in that After S5, it further includes: S6: After the jacket is installed in the sea area where the jacket is in service, obtain the measured axial force and bending moment of the monitoring points of the members through the monitoring data of the sensors, so as to obtain the deviation between the theoretical axial force and bending moment and the measured axial force and bending moment based on the theoretical axial force and bending moment of the monitoring points of the members, so as to guide the staff at the construction site of the relevant projects for the subsequent layout of the jacket to correct the layout of the sensors.

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